[ ghc-Feature Requests-1189559 ] incomplete patterns and GADT

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Feature Requests item #1189559, was opened at 2005-04-25 08:29
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Category: None
Group: None
Status: Open
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: incomplete patterns and GADT

Initial Comment:
I would like to compile with 
-fwarn-incomplete-patterns and use GADTs, 
but I have bogus error messages. 
Suppose I define : 
 
data T a where 
    C1 :: T Char 
    C2 :: T Float 
 
then a function : 
 
exhaustive :: T Char -> Char 
exhaustive C1 = ' ' 
 
If I compile with incomplete pattern warnings, 
I get that my function "exhaustive" is not 
exhaustive. 
But if I add a case : 
 
exhaust C2 = ' ' 
 
then the compiler accurately warns me that this 
case is inaccessible. 
Would it be possible to add the accessibility check 
when compiling with incomplete patterns detection ? 

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